Manufacturing method and apparatus of fiber reinforced composite member

ABSTRACT

There is disclosed a method of forming a fabric  1  on the surface of a mandrel  10 , infiltrating the formed fabric with matrix, and leaving portions  12   a,    12   b  of the mandrel as integral with the fabric and removing the mandrel before the fabric adheres to the mandrel by matrix infiltration. Subsequently, a remaining portion of the mandrel is used as a reference surface and machining is performed. Without possibility of adhesion to the mandrel and resulting breakage, machining bases (axial center and reference surface) during machining can accurately be provided, and this can largely enhance machining precision and yield of a final product.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a manufacturing method andapparatus of a ceramic matrix composite member and carbon-basedcomposite material which can accurately be provided with machining bases(axial center and reference surface) during machining.

[0003] 2. Description of the Related Art

[0004] In order to raise the performance of a rocket engine usingNTO/N₂H₄, NTO/MMH, and the like as impelling agents, heat-resistanttemperature of a combustor (thrust chamber) is requested to be raised.For this purpose, a coated niobium alloy having a heat-resistanttemperature of about 1500° C. has heretofore been used as a chambermaterial for many rocket engines. However, this material isdisadvantageously heavy because of its high density, low inhigh-temperature strength, and has a short coating life.

[0005] On the other hand, since ceramic is high in heat resistingproperties but disadvantageously brittle, a ceramic matrix compositemember (hereinafter abbreviated as CMC) has been developed byreinforcing the ceramic with ceramic fiber. Specifically, a ceramicmatrix composite member (CMC) comprises ceramic fiber and ceramicmatrix. Additionally, in general the CMC is indicated as ceramicfiber/ceramic matrix by its material (e.g., when both are formed of SiC,SiC/SiC is indicated).

[0006] Since CMC is light-weight and high in high-temperature strength,it is a remarkably prospective material for the combustor (thrustchamber) of the rocket engine, further a fuel piping in ahigh-temperature section, a turbine vane of a jet engine, a combustor,an after-burner component, and the like.

[0007] However, the conventional CMC cannot hold its hermetic propertiesand is disadvantageously low in resistance to thermal shock.Specifically, for the conventional CMC, after a predetermined shape isformed of ceramic fibers, a matrix is formed in a gap between the fibersin so-called chemical vapor infiltration (CVI) treatment. However, aproblem is that it takes an impractically long time (e.g., one year ormore) to completely fill the gap between the fibers by the CVI.Moreover, in a high-temperature test or the like of the conventional CMCformed as described above, when a severe thermal shock (e.g.,temperature difference of 900° C. or more) acts, the strength isdrastically lowered, and the CMC can hardly be reused.

[0008] Therefore, the conventional ceramic matrix composite member (CMC)cannot substantially be used in the combustor (thrust chamber), the fuelpiping or another component requiring the hermetic properties andresistance to thermal shock.

[0009] In order to solve the aforementioned problem, the presentinventor et al. have created and filed a patent application,“Ceramic-based Composite Member and its Manufacturing Method” (JapanesePatent Application No. 19416/1999, not laid yet). The Ceramic-basedComposite Member can largely enhance the hermetic properties and thermalshock resistance and which can be for practical use in the thrustchamber, and the like. In the invention, as schematically shown in FIG.1, after subjecting the surface of a shaped fabric to CVI treatment toform an SiC matrix layer, PIP treatment is performed to infiltrate andcalcine a gap of the matrix layer with an organic silicon polymer as abase.

[0010] In a manufacture process shown in FIG. 1, from a braiding process(1) to a CVI process (3), a jig or mandrel, for example, of carbon orthe like is used to form a fabric 1 in a periphery and subsequently, theCVI treatment is performed. Since matrix is formed in the gap of thefabric 1 by the CVI treatment and a shape is held, in this stage, themandrel is detached, and subsequent PIP treatment (4) and machining (5)are performed in a conventional art. Additionally, in the braidingprocess, as schematically shown in FIG. 2, for example, braid weave isused in which a braided thread is alternately and obliquely woven into amiddle thread.

[0011] However, a ceramic matrix composite member 2 subjected to the CVItreatment and PIP treatment after the braiding process (e.g., braidweave) is large in surface concave/convex, and there is a problem that amachining basis cannot be established. Specifically, as schematicallyshown in FIG. 3, since the concave/convex of the surface of asemi-finished product (ceramic matrix composite member 2) is large, amachining reference point/surface cannot precisely be defined, and forexample, by determining an axial center in such a manner that deflectionof rotation around Z-Z axis of FIG. 3 is minimized, and furtherdetermining, for example, a minimum diameter position in this situation,the position is set as a positioning basis of an axial direction.Therefore, in such method, it is impossible to accurately determine theaxial center or the reference surface of the axial direction, and as aresult, a defect of a cut place of the axial direction, non-uniformityof a product plate thickness by one-side contact machining (cut ofreinforced fiber) and other machining precision defects are caused.

[0012] Moreover, in order to solve the problem, it is preferable toattach the mandrel even during machining, but in this case, the productadheres to the mandrel by the matrix in the CVI or PIP treatment, itbecomes difficult or impossible to detach the product, and there is aproblem that product breakage rate increases and product yields areremarkably lowered.

SUMMARY OF THE INVENTION

[0013] The present invention has been developed to solve the problem.Specifically, an object of the present invention is to provide amanufacturing method and apparatus of a fiber reinforced compositemember in which machining bases (axial center and reference surface)during machining can accurately be provided without possibility ofadhesion to a mandrel and resulting breakage, so that machiningprecision and yield of a final product can largely be improved.

[0014] According to the present invention, there is provided amanufacturing method of a fiber reinforced composite member comprisingsteps of: forming a fabric on the surface of a mandrel; infiltrating theformed fabric with matrix; and leaving a part of the mandrel which isintegral with the fabric and removing the mandrel.

[0015] According to a preferred embodiment, the left part of the mandrelwhich is integral with the fabric is used as a reference surface toperform machining. Moreover, the fabric is formed to be longer than aproduct dimension.

[0016] According to the method of the present invention, since a part ofthe mandrel is left as integral with the fabric and the mandrel isdetached, a product portion failing to contact the left mandrel cansufficiently be infiltrated with the matrix and formed similarly as aconventional art. Moreover, since a part of the mandrel is left in asemi-finished product (fiber reinforced composite member) after matrixinfiltration treatment, by using the part of the mandrel as themachining bases (axial center and reference surface) during machining,an axial direction position and axial center determined on the mandrelcan be held constant. Therefore, by setting the reference surfacebeforehand to be a smooth surface, even with a large concave/convex ofthe surface of the semi-finished product, the machining basis canaccurately be provided, non-uniformity of a machined plate thickness canbe eliminated, shape precision is improved, and further strengthdeterioration by cutting of fiber can be inhibited.

[0017] Moreover, according to the present invention, there is provided amanufacturing apparatus of a fiber reinforced composite member forforming a fabric on the surface of a mandrel, and infiltrating theformed fabric with matrix, wherein the mandrel is formed to be longerthan a product dimension of a fiber reinforced composite member.

[0018] According to the preferred embodiment of the present invention, aportion of the mandrel protruding from the product dimension of thefiber reinforced composite member has a portion whose diameter increasestoward an end, and the diameter increasing portion can be separated intoan annular portion having a diameter larger than an outer diameter of aproduct dimension end portion and a remaining portion in a constitution.

[0019] By the constitution, the annular portion having the diameterlarger than the outer diameter of the product dimension end portion isleft as integral with the fabric, and the remaining portion can beremoved.

[0020] Moreover, it is preferable to form a groove or a protrusioninterlocking with the fabric on the surface of the annular portion insuch a manner that when the part of the mandrel forming the productportion is removed, the mandrel left as integral with the fabric failsto move on the fabric. By this constitution, connection/integration ofthe annular portion with the fiber reinforced composite member isreinforced, and displacement of the annular portion during removing ofthe mandrel can be prevented.

[0021] Other objects and advantageous characteristics of the presentinvention will be apparent from the following description with referenceto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a schematic view of a CMC manufacturing method to whichthe present invention is applied.

[0023]FIG. 2 is a schematic view of a braid weave.

[0024]FIG. 3 is a schematic view of a machining basis in a conventionalmanufacturing method.

[0025]FIG. 4 is a schematic view of a mandrel constituting a manufactureapparatus of the present invention.

[0026]FIGS. 5A and 5B are schematic views of the manufacturing method inwhich a mandrel 10 of FIG. 4 is used.

[0027]FIG. 6 is a precision comparison diagram according to anembodiment of the method of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] A preferred embodiment will be described hereinafter withreference to the drawings.

[0029]FIG. 4 is a schematic view of a mandrel constituting a manufactureapparatus of the present invention. As shown in FIG. 1, in amanufacturing method and apparatus of a fiber reinforced compositemember of the present invention, after forming a fabric 1 on the surfaceof a mandrel 10, and performing a CVI treatment to form an SiC matrixlayer on the surface of the formed fabric 1, a PIP treatment isperformed to infiltrate a gap of the matrix layer with an organicsilicon polymer as a base material and perform calcining.

[0030] In the manufacturing method and apparatus of the presentinvention, as shown in FIG. 4, the mandrel 10 is in a division structureconstituted by a combination of reference segments 12 a, 12 b providedwith reference surfaces 11 a, 11 b and other forming segments 14 a, 14b. Specifically, in this example, the forming segments 14 a, 14 b aredivided at a smallest portion 14 c of a product portion, and areintegrally assembled by a connecting rod 16 passed through a centerportion and nuts 17 fitted to both ends of the rod.

[0031] Moreover, the end surface 11 a of an axial direction of thereference segments 12 a, 12 b is formed to be vertical with an axialline Z-Z of a product, and forms a reference surface of an axial centerduring machining as described later. Furthermore, the inner surface libof the reference surfaces 12 a, 12 b is a cylindrical surface which iscoaxial with the axial line Z-Z, and forms a reference surface of theaxial center during machining.

[0032] The reference segments 12 a, 12 b are joined to each other insuch a manner that there is little gap outside a cylindrical portionprovided in the forming segments 14 a, 14 b.

[0033]FIGS. 5A and 5B are schematic views of a manufacturing method inwhich the mandrel 10 of FIG. 4 is used. In the drawing, FIG. 5A shows aprocess of forming the fabric 1 on the surface of the mandrel 10 to aprocess of performing the CVI treatment to further form the SiC matrixlayer on the surface of the formed fabric 1. Moreover, FIG. 5B shows asubsequent situation in which the reference segments 12 a, 12 b are leftas integral with the fabric 1 and the forming segments 14 a, 14 b areremoved before the PIP treatment. Machining may be performed in anystage of the CVI, PIP process. Additionally, removing of the formingsegments 14 a, 14 b may be performed after or while the CVI treatment isperformed.

[0034] As shown in FIG. SA, connection portions 2 a, 2 b with a diameterlarger than that of the product portion are prepared outside the productportion of a ceramic matrix composite member 2, and the connectionportions may be connected to the reference segments 12 a, 12 b of themandrel 10.

[0035] Moreover, the reference segments 12 a, 12 b are provided with athrough hole 13 (corresponding to the inner surface lib of the referencesegments 12 a, 12 b in this example) which is concentric with theproduct portion and is larger in diameter than the product portion, andthe forming segments 14 a, 14 b for forming the product portion may beconstituted to be detached through this through hole.

[0036] Furthermore, as shown in FIGS. 4, 5A and 5B, the surface of thereference segments 12 a, 12 b may be provided with grooves 15 a, 15 band protrusion to enhance connection strength with the fabric 1. For thegrooves 15 a, 15 b, in this example, only one groove is provided in aperipheral direction. However by disposing a plurality of grooves, fiber(e.g. a braid thread) of the fabric 1 can be joined into this groove soas to reinforce connection/integration of the reference segments 12 a,12 b of this portion with the ceramic matrix composite member 2.Additionally, by coating the surface of the reference segments 12 a, 12b beforehand with an adhesive (e.g., a polymer solution in the PIPtreatment), the grooves 15 a, 15 b and protrusion may be omitted.

[0037] In the method of the present invention, the mandrel 10 with thefabric 1 formed on the surface thereof is in the division structureconstituted by the combination of the reference segments 12 a, 12 bprovided with the reference surfaces 11 a, 11 b and other formingsegments 14 a, 14 b. Before the fabric 1 adheres to the mandrel 10 bymatrix infiltration, the reference segments 12 a, 12 b are left asintegral with the fabric 1 and the forming segments are removed.Therefore, the product portion which fails to contact the referencesegment can sufficiently be subjected to the matrix treatment similarlyas the conventional art.

[0038] Moreover, since the reference segments 12 a, 12 b are left in thesemi-finished product (ceramic matrix composite member 2) duringmachining, by using the reference surfaces 11 a, 11 b of the referencesegments as machining bases (axial center and reference surface), theaxial direction position and axial center determined on the mandrel canbe held constant. Therefore, by setting the reference surface beforehandto be a smooth surface, even with a large concave/convex of the surfaceof the semi-finished product, the machining bases can correctly beprovided, non-uniformity of a plate thickness after machining can beeliminated, shape precision is improved, and further strengthdeterioration by cutting of fiber can be inhibited.

[0039]FIG. 6 is a precision comparison diagram according to anembodiment of the method of the present invention. In FIG. 6, theabscissa indicates the axial direction position of a manufactured thrustchamber, and the ordinate indicates tolerances of plate thickness andshape.

[0040] From this drawing, the plate thickness tolerance and shapetolerance according to the conventional method are both dispersedsubstantially in a range of +0.5 mm or more, and fail to reach a targetof +0.25 mm or less. On the other hand, the plate thickness toleranceand shape tolerance according to the method of the present invention aresubstantially within the target of +0.25 mm or less.

[0041] As described above, in the manufacturing method and apparatus ofthe present invention, the machining bases (axial center and referencesurface) during machining can accurately be provided without possibilityof adhesion to the mandrel and resulting breakage, so that machiningprecision and yield of a final product can largely be improved, andother superior effects are provided.

[0042] Additionally, the present invention is not limited to theaforementioned embodiment and can of course be modified variouslywithout departing from the scope of the present invention. For example,in the above description, the thrust chamber or another rotary member asthe product has been described in detail, but the present invention isnot limited to this, and can also be applied to an arbitrary-shape fuelpiping, turbine vane, combustor, afterburner component, and the like.

What is claimed is:
 1. A manufacturing method of a fiber reinforcedcomposite member comprising steps of: forming a fabric on the surface ofa mandrel; infiltrating the formed fabric with matrix; and leaving apart of said mandrel which is integral with the fabric and removing themandrel.
 2. The manufacturing method of a fiber reinforced compositemember according to claim 1 , comprising steps of using the left part ofsaid mandrel which is integral with the fabric as a reference surface toperform machining.
 3. The manufacturing method of a fiber reinforcedcomposite member according to claim 1 or 2 wherein said fabric is formedto be longer than a product dimension.
 4. A manufacturing apparatus offiber reinforced composite member for forming a fabric on the surface ofa mandrel, and infiltrating the formed fabric with matrix, wherein saidmandrel is formed to be longer than a product dimension of a fiberreinforced composite member.
 5. The manufacturing apparatus of fiberreinforced composite member according to claim 4 wherein a portion ofsaid mandrel protruding from the product dimension of the fiberreinforced composite member has a portion whose diameter increasestoward an end, and the diameter increasing portion can be separated intoan annular portion having a diameter larger than an outer diameter of aproduct dimension end portion, and a remaining portion.
 6. Themanufacturing apparatus of fiber reinforced composite member accordingto claim 4 or 5 wherein a groove or a protrusion interlocking with saidfabric is formed on the surface of said annular portion in such a mannerthat when a part of the mandrel forming a product portion is removed,the mandrel left as integral with the fabric fails to move on thefabric.